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CVR(T) Final Drive

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I'm helping a friend sort out the final drives on his Scimitar. They've both been leaking oil onto the brakes. We pulled the LH drive off the tank and upon pulling the input shaft found that the seal had been compromised by sand and similar foreign material and the rubber seal is worn. Its a pretty poor design but we're working with what we've got. Given the ingress of sand i elected to open up the box. Oil seals are easily sorted, but we're now interested to hear the forums opinions / experience of what we found. The three planet gears each revolve on a shaft which has been made with a recess in each end forming a kind of 'tubular' end to the shaft with presumed design intent being that the tubular bit is 'peened' outwards  to stop the shaft moving along its axis. However, we found that two of the planet shafts have been installed with this assumed design intent but one hasn't been 'peened' at all allowing it to drift longitudinally and interface unintentionally with the inside of the box wearing down the 'tubular' section of the shaft at that end.

So, we're wondering if anyone has encountered this below par assembly of the box before and if theres any chance of getting a new planet gear shaft?

Thanks. Richard






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Well, now you know which side the shaft drifts toward when not peened.  So, if you peen the non-worn side a bit and reinstall the pin in it's previous orientation, it should pull as before but be constrained against further wear.

Of course, I'm sure plenty of folks have replacement pins.

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Yeah thats a possibility. We haven't made enquiries yet, and theres probably complete final drives about, but i'm not sure anyone stocks individual parts of gearboxes like these. Will start ringing around.

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In my opinion, you will be very lucky to source the pins.  This is because in service, if there was a problem with the final drive, the whole unit would be replaced.  The final drive would then be sent away for base overhaul.  This may be even by the manufacturer..  That might be David Brown but I don't now.  Their military dept would know straight away if they made then.  You never know, they might supply you.

The pins do not look to be too difficult to make. EN24T, rough turn, heat treat, (harden & temper) then grind to finished size. 


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John, thats exactly what i suspected.

I tried contacting RBSL who still advertise the CVR(T) range on their website but not had a reply and they'd probably charge a small fortune for one little pin anyway.

Yes, making a new pin is an option we've looked into. Up to the owner at the end of the day. Hardening isn't really my area of expertise, haven't done it since college. I had some bits for my scammells clutch hardened and it was a bit pricey.

Looks like David Brown is now David Brown Santasalo.

Thanks anyway. Richard

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